• Keika Mukaihara, Maiko Hasegawa-Moriyama, and Yuichi Kanmura.
• Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan.
• J Anesth. 2017 Dec 1; 31 (6): 829-836.

PurposePerioperative analgesia during thoracotomy is often achieved by combining paravertebral block (PVB) with general anesthesia (GA). Functional near-infrared spectroscopy (NIRS) can detect changes in cerebral oxygenation resulting from nociceptive stimuli in the awake state or under sedation. We used NIRS to measure changes in cerebral blood flow provoked by thoracotomy incision made under GA and determine how these changes were influenced by supplementation of GA with PVB.MethodsThirty-four patients undergoing elective thoracotomy were enrolled. Patients were randomly assigned to a group receiving only GA, or GA combined with PVB (GA + PVB). Changes in cerebral oxygenated hemoglobin (ΔO2Hb), deoxygenated-Hb (ΔHHb), and total-Hb (ΔtotalHb) were evaluated by NIRS as surgery began.ResultsIn the GA group, ΔO2Hb was significantly higher in the hemisphere contralateral to the side of surgery when the incision was made and 2 min after incision compared with the ipsilateral side (start of surgery, P < 0.01; 2 min, P < 0.05). In contrast, there were no significant changes in the ΔO2Hb at any of the time points in the GA + PVB group. Comparable with ΔO2Hb, the concentration of ΔtotalHb was significantly higher in the contralateral hemisphere in the GA group at the start of surgery (P < 0.05).ConclusionsChanges in the cerebral O2Hb concentration were detected by NIRS immediately after surgical incision under GA, but not in the presence of a PNB. NIRS could be used to monitor surgical pain. PVB inhibited changes in oxygenation induced by incision-provoked pain.

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